Is the function os. add_dll_directory() adding directories permanently?

Question

For loading DLL libraries in Python 3.8+ I understand the the path environemnt variable is not used anymore to search for dependencies. Therefore the function os. add_dll_directory() should be used to add directories to the search path. That works on my machine.

Is it possible that the directories are added permanently? I have noticed that now everything is loaded correctly also without adding the dll directory first using the function mentioned. I cannot reproduce the error where the dependencies were not found.

From the documentation I did not understand that anything is changed permanently.

Answer 1

[Python.Docs]: os.add_dll_directory(path) calls [MS.Docs]: AddDllDirectory function (libloaderapi.h) which states ( emphasis is mine):

Adds a directory to the process DLL search path.

So, it has effect during the lifetime of the calling process, or (according to Python doc ) until the returned object is closed (in that case RemoveDllDirectory is called under the hood) either manually or at with statement exit.